The invention lies in the field of microcircuit cards suitable for interfacing with a contactless communication module in a terminal.
It should be recalled firstly that the ISO 7816 standard is a standard with very widespread use, in particular in certain secure documents, and in the microcircuit cards used in telecommunications (universal integrated circuit card (UICC) modules or embedded UICC (eUICC) modules) or for making bank transactions secure (smart cards).
It should be observed that a eUICC may be a microcircuit soldered directly to the printed circuit of the telephone.
In particular, the ISO 7816 standard defines protocol layers at “physical”, “transport”, and “application” levels for enabling communication to be set up between the microcircuit card and a terminal or reader with which the microcircuit card is connected.
The protocol layers at the “transport” and “application” levels enable communication channels to be set up between the microcircuit card and the terminal so that those entities can exchange messages.
FIG. 1 shows a startup sequence of the ISO 7816 standard between a microcircuit card 100 and a terminal 200, in accordance with the prior art. The communication is communication of the master/slave type, in which the microcircuit card replies (REP general message) to commands (CMD general message) from the master terminal. Thus, by way of example, the microcircuit card replies with the message “ATR T=1” to the “reset” command from the terminal.
In such communication of the master/slave type, the microcircuit card cannot take the initiative of sending a message; it must necessarily wait for a command from the terminal in order to communicate therewith.
Since the microcircuit card is necessarily inactive between two command/reply exchanges, in order to save energy, the terminal can decide to cease powering the microcircuit card during the time interval between receiving a reply from the card and sending the next command to the card.
That can lead to problems if the unpowered card has operations to perform during those time intervals. In order to avoid such drawbacks, the ISO 7816 protocol provides a mechanism whereby the microcircuit card can use a “procedure byte” provided for this purpose in the transport frames in order to request the terminal to provide power for an additional period of time so as to be able to perform operations.
New generations of microcircuit card are also known that are suitable for communicating with a contactless front end (CLF) communication module using the single wire protocol (SWP) defined in the European Telecommunications Standards Institute (ESTI) document TS 102 613 V9.2.0 and shown in FIG. 2. It should be noted with reference to this figure that the SWP interface provides communication in full duplex mode between the microcircuit card and the contactless communication module, in which:                the signal S1 is a voltage modulated digital signal for messages sent by the contactless communication module 200 to the microcircuit card 100; and        the signal S2 is a current modulated digital signal for messages sent by the microcircuit card 100 to the contactless communication module 200.        
FIG. 3 shows the hardware implementation of the SWP interface of FIG. 2, as described in Chapter 5.1 of ETSI document TS 102 613 V9.2.0.
Unfortunately, the SWP protocol does not provide a mechanism equivalent to in the one of the above-described ISO 7816 protocol which aims at enabling a microcircuit card 200 to request the contactless communication module 100 to continue to power it outside periods needed for master/slave type exchanges between those entities.
Consequently, the present state of the art does not provide a solution for a microcircuit card for guarantying that it will be powered by the terminal to which it is connected via an SWP interface for a length of time that is sufficient to enable it to carry out an internal operation in full.
The present invention seeks to provide a mechanism that does not present the above-mentioned drawbacks.